1. Field of the Invention
This invention relates to a method and apparatus for simultaneously driving numerous microbodies having dimensions in the order of several nanometers, micrometers or millimeters that can be utilized in such fields as engineering, medicine and pharmacology as a source of motive power for artificial muscles and ultrasmall mechanisms and the like, such as micromachines, nanomachines and controlled-release pharmaceuticals, for example.
2. Description of the Prior Art
As conventional methods of driving microbodies, there are known methods such as those that utilize piezoelectric elements, or electrostatic or ultrasonic motors, or optical forceps formed by finely collimated light beams. More recently a fine probe such as that of a scanning tunneling microscope (STM) or atomic-force microscope (AFM) has been used to manipulate microscopic particles, atoms and molecules.
The above-mentioned conventional techniques that can drive the smallest bodies are the optical forceps method, the STM method and the AFM method. In the case of the optical forceps method it is necessary to aim a fine, external light beam at the particle to be driven. The light beam has to be very fine to match the microscopic dimensions of the particles being handled, so means such as a microscope is used to focus the beam to the requisite fineness. It follows, therefore, that in order to simultaneously drive numerous microbodies, it is necessary to use numerous fine light beams, and that a method of using these beams to scan the particles at high speed is needed. The result is that it becomes necessary to use a very large external apparatus to move a microscopic body the smallest of distances. Even if, instead of the numerous light beams, an optical scanning arrangement were to be used in which the beam intensity was modulated on a time basis, the result would still be the use of large peripheral devices to drive microscopic bodies. The same problem arises with respect to the STM and AFM methods, as both require the use of a fine probe, and preparing this probe requires the use of large peripheral devices.
Also, while piezoelectric elements can be used to control quite small bodies, again, quite a large external piezoelectric element is required for the slightest movement of a microscopic body.
The problem is the same with ultrasonic motors, because of the large size of the elements used. With an ultrasonic motor, an ultrasonic wave is focused on a particle of interest to move the particle. However, ultrasonic waves cannot be focussed on a point with the same precision as a light beam, and this relatively lower precision restricts the particles that can be controlled by ultrasonic waves to those having a size in the micrometer range, so a problem with this method is that it cannot be applied to smaller particles, that is, to nanometric particles.
Electrostatic motors, ultrasonic motors, piezoelectric elements and the like all require an array of electrodes or oscillators, each of which is about the same size as the body to be driven. As such, the smaller the size of the bodies which are to be driven, the more difficult it is to fabricate such electrode or oscillator arrays, and as the electrodes or oscillators have to be connected to enable them to be electrically energized, the structure is complex.